Flat no-leads packages such as QFN (quad-flat no-leads) and DFN (dual-flat no-leads) physically and electrically connect integrated circuits to printed circuit boards (PCBs) (see: Wikipedia.org). Flat no-leads, also known as micro leadframe (MLP) and SON (small-outline no leads), is a surface-mount technology, one of several package technologies that connect ICs to the surfaces of PCBs without through-holes. Flat no-lead is a near chip scale package plastic encapsulated package made with a planar copper lead frame substrate. Perimeter lands on the package bottom provide electrical connections to the PCB. Flat no-lead packages include an exposed thermal pad to improve heat transfer out of the IC (into the PCB). Heat transfer can be further facilitated by metal vias in the thermal pad.
The QFN package includes an insulating encapsulation that limits the heat dissipation and fails to block radiated emissions from the integrated circuit enclosed in the package.